textproduct: Rapid City

KEY MESSAGES

- Breezy conditions will develop across portions of northeastern Wyoming and northwestern South Dakota Friday into Friday night, with a few gusts as high as 40 MPH.

- Friday night has trended drier, with only a 10% chance of a light, low-impact rain shower as a weak disturbance moves through.

- Potential for elevated to near-critical fire weather conditions this weekend over large portions of the area due to gusty winds, low relative humidities, and warm temperatures is increasing. An isolated thunderstorm or two also remains possible, with low confidence.

- The next chance for meaningful precipitation arrives Monday into Tuesday, though amounts remain uncertain.

UPDATE

Issued at 1024 PM MDT Thu Apr 9 2026

No major changes to the forecast were needed this evening. We continue to expect breezy southeast winds to develop Friday afternoon into Friday night across portions of both northeastern Wyoming (favorite area of the HREF) and northwestern South Dakota (favorite area of the NBM), with NBM guidance continuing to suggest a 50-70% chance of gusts exceeding 45 MPH over northwestern SD. However, the area at greatest risk for these peak gusts is relatively small in areal coverage (south of Buffalo, west of Faith, north of Rapid City) with peak winds potentially only getting that high for a few hours, which gives us pause about considering a Wind Advisory (not to mention it would be a pretty marginal one). In addition, most model guidance is coming in lower than the NBM...HREF ensemble MAX wind gusts only reach about 40 MPH, not a single GFS ensemble member gusts to 45 MPH at Buffalo (with ECMWF gusts even lower), and the NAM is pretty light as well. As such, we will forecast and message the potential for a few gusts of 35-40 MPH...otherwise it's a typical breezy day in South Dakota with no advisory currently planned. A very weak disturbance may still be able to kick off a couple light showers Friday night, but most guidance has trended even drier. Potential is now about 10%, with essentially no QPF. Moving forward and watching high temperatures on Saturday and Sunday...we continue to note the NBM 25th-75th percentile range coming in entirely above (warmer than) the deterministic NBM (which can be a sign the blend is struggling to "catch up" with a pattern change/fast warm-up), although our blended forecast has nudged a degree or two warmer compared to this time yesterday, and raw model guidance is running cooler/closer to our current forecast. There may also be some cloud cover running around which can certainly take the edge off full heating potential. Will continue to stay the course with our forecast and watch trends, but the potential remains for highs in some spots to top out several degrees warmer than currently forecast...Rapid City could approach 90 degrees as a high-end scenario. Finally...overall potential/confidence is increasing in critical fire weather conditions Saturday and Sunday due to the very warm temperatures, gusty winds, and low relative humidities. RH values will be highest and least favorable over the northwestern South Dakota Plains, but overlap of critical conditions (winds/RHs) is possible for most of the rest of the region from northeast Wyoming, across the Black Hills, and into our east-central and southwestern SD plains fire zones. Models continue to support decent instability and thus an isolated thunderstorm concern, but lack of moisture continues to look like a potential limiting factor.

DISCUSSION

(This Evening Through Thursday) Issued at 1237 PM MDT Thu Apr 9 2026

Current upper-air water vapor analysis depicts split-flow across CONUS, with troughing stretching from eastern MT to MI and short- wave ridging located within the trough (over MN). The low over northern ND has shifted northeast, while the next low expected to impact the region (Saturday/Sunday) is located off the northern CA/OR coast. WV imagery indicates bands of cloud cover crossing the region with radar showing light returns from light rain/snow showers over north-central SD. Current surface observations show temperatures in the 30s and 40s with generally easterly winds of 10 to 20 kts, gusting to 30 kts. RH values are decreasing across southwestern SD and northeastern WY as drier air moves into the region under ridging to the west.

Friday will see continued warming as high pressure and ridging move over the region, along with a slight chance for precipitation Friday evening/night (<20 percent chance for >0.01, NBM CONUS) for the Black Hills and south-central SD. Windy conditions will develop Friday afternoon across northwest SD with chances for wind gusts exceeding 45 mph (55 to 75 percent chance, NBM CONUS).

Highs Saturday and Sunday creep into the 80s (55 to 75 percent chance Saturday/ 30 to 45 percent chance Sunday) along with elevated, possibly near-critical, fire weather conditions returning. RHs will bottom out around 16 percent Saturday and drop even lower Sunday, down to 12 percent, across southwestern SD and parts of northeastern WY. Breezy winds are expected across the SD plains both days, which may warrant a Red Flag Warning for one, if not both days. Along with the fire weather, there will be chances for showers, and possibly a few thunderstorms, Saturday afternoon/evening, however, available moisture may be limited.

The next chance for meaningful moisture arrives with a trough/low moving through Monday/Tuesday. The current NBM-CONUS run has much of western SD at a 45 to 55 percent chance for a 0.25 of an inch from the system. However, precipitation amounts will likely be lower due to the dry conditions that have persisted for the region.

AVIATION

(For the 06Z TAFS Through 06Z Friday Night) Issued At 1024 PM MDT Thu Apr 9 2026

The evening forecast is on track with winds now becoming very light at KRAP and KGCC. Confidence remains high in dry, VFR conditions throughout the TAF period as brief shortwave high pressure takes control. High-level clouds will increase from FEW to BKN from the southwest Friday afternoon and evening as a very weak disturbance approaches, along with an increase in southeasterly winds Friday initiating a bit earlier than the normal diurnal cycle (starting between 15-17z/9-11am and continuing into Friday evening). Even with these trends, confidence in VFR conditions remains high through sunset Friday night. Our next, very low chance of showers (associated with that disturbance we just mentioned) crosses the region Friday night near and just beyond the current TAF period, but most areas should hold dry with terminals that do pick up a brief shower seeing little to no QPF, and absolutely no impact on vsbys. Also still watching a small, low-confidence chance of an isolated thunderstorm Saturday afternoon/evening.

FIRE WEATHER

Issued At 1237 PM MDT Thu Apr 9 2026

Elevated to near-critical fire weather conditions are expected this weekend across southwestern South Dakota and northeastern Wyoming. Highs will be in the upper 70s to low 80s with afternoon relative humidity values falling into the teens, with locally lower values possible Sunday. Breezy winds are expected both days, which may lead to periods of critical conditions and potential Red Flag concerns. While there will be chances for light rain showers and isolated thunderstorms, a wetting rain is not likely.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.